Bag-filling apparatus



Feb, 19, 1957 J. H. BRADFORD 2,781,799

BAG-FILLING APPARATUS Filed May 14. 1951 2 Sheets-:Sheet l I HF/G. 2.

r 33 1/ 1 g 23 I Y 1/ 2H 27a 3nnentor: JAMES H. BRADFORD,

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Feb. 19, 1957 J. H. BRADFORD BAG-FILLING APPARATUS 2 Sheets-Sheet 2 Filed May 14. 1951 GPA 3nventor;

0 D m A United States Patent BAG-FILLING APPARATUS Application May 14, 1951, Serial No. 226,191

10 Claims. (Cl. 141-68) This invention relates to the bagging of lightweight and fragile granules.

In the production and marketing of the exceedingly lightweight and fragile insulating granules known as expanded perlite, I have found that conventional bagging procedures do not produce satisfactory results. The filled bags are cylindrical in configuration, which is a great disadvantage in handling and storage. Not only do they occupy more space when stacked than do bags having a flattened configuration, but they tend to roll out of place when being transported by truck or freight car. Furthermore, the cylindrical bags are unwieldy to handle. In spite of their light weight, they are not easy to carry or to otherwise move from place to place.

If it were not for the physical characteristics of this material-chiefly its very light weight and, to a lesser extent, its rough surfaces and fragile natureit would be possible to solve these problems by reducing the quantity of material placed in a bag, thereby enabling material flow within a bag to naturally provide the desired flattened configuration upon laying of the bag on its side, as in piling or stacking for transportation. This is customarily done for heavier materials, such as cement, grain, and the like.

With perlite insulating granules, however, a very considerable amount of space would have to be left in order to obtain appreciable natural flattening of the bag. Even if this were economically feasible, which it is not, there would be undesirable attrition and breakage of the individual granules, destructive of the quality of the material. Accordingly, the industry has reluctantly accepted the disadvantage of cylindrical bags, while seeking a satis-' factory solution of the problems presented.

Coinc-idental with the above problems is the additional undesirable practice of overstufiing the bags in order to get as much weight as possible in the available space, with a View toward obtaining minimum carload rates for transportation. This not only accentuates the cylindrical configuration, but pulverizes many of the fragile granules, resulting in diminution of quality and added possibilities for attrition and further granule breakage during subsequent handling of the bags.

Through the course of considerable experimentation, I have found that the difiiculties inherent in conventional bagging procedures, and in present practices of the industry, can be overcome, and that excellent results can be obtained, if, during the operation of a standard valvebag filling machine of material-packing type, opposing major areas of opposite broad panel walls of the bag are held firmly against outward expansion beyond predetermined limits of flatness, and if, further, the filling operation is carried to the extent of substantially completing and snugly filling the bag, but is immediately halted upon the exertion of excessive force by the material-feed element of the machine.

The resulting filled bag is characterized by a tightly encased rigidity of contents, which substantially com- "ice pletely prevents individual particle movement within the bag, and which, therefore, preserves the preformed fiattened configuration throughout all phases of normal handling.

The jarring or vibrating action of the machine on the bag and contents during the filling operation, combined with filling of the bag to maximum capacity, but not beyond, rneans that the accompanying forced forming or shaping of the bag achieves a lasting effect. Furthermore, it means that desired maximum loading of each bag is obtained, with minimum breakage of the fragile granules, and without resulting in the customary cylindrical configuration.

I have found that the essentially rigid bags of perlite obtained from the bag-filling procedure outlined above, not only hold their shape, but effectively resist breakage of the fragile granules during handling. Thus, the product arrives at the point of consumption-in prime condition, its quality unimpaired.

I prefer to carry out my improved bagging procedure by the use of a standard valve-bag filling machine of material-packing type, which has been structurally adapted for the purpose by certain significant additions. A machine of this type especially well suited to the purpose is equipped with a screw feed and with a sacking platform arranged for vibration. In this connection, I am aware that bag-forming or shaping plates have been heretofore proposed as optional equipment for such a machine in certain special instances of use not involving those problems faced by the perlite processing industry, and not involving additional structural features essential to the achievement of the results sought and obtained by the present invention.

Thus, the additions to a standard machine, essential for automatically and necessarily obtaining the results of this invention, consist of bag-forming or shaping platesor their equivalent-in functional combination with a feeder shut-off control, regulatable in conformity with drive power requirements and actuatable in response to limited excessive power requirements above a pre-established norm.

In accordance with my invention, I not only provide bag-forming or shaping plates operable to prevent outward expansion of opposing major areas of opposite broad panel walls of the bag beyond predetermined limits of flatness, but I additionally provide a sensitive relay in one leg of the electrical power supply circuit of the feed drive motor, responsive to limited excessive current draw. For convenience of adaptation to individual requirements, I make the relay adjustable in its response to such excessive current draw, for example, by balancing performance of the relay coil against adjustable spring tension of a spring-loaded armature arranged to open and close the power supply circuit.

Further objects and features of the invention will be come apparent from the following detailed description of the typical and preferred embodiment of the apparatus illustrated in the accompanying drawings.

In the drawings:

Fig. 1 represents a perspective view, looking toward the front and one side, of the apparatus as it appears when not in operation, a portion of the casing being broken out to reveal otherwise hidden parts;

Fig. 2, a top plan;

Fig. 3, a front elevation showing a durable paper bag of standard valve type in the process of being filled;

Fig. 4, a fragmentary side elevation of the showing in Fig. 3;

Fig. 5, a perspective view of a filled bag as it appears following its removal from the apparatus;

Fig. 6, a longitudinal section taken on the line 66 of Fig. and

Fig. 7, a schematic wiring diagram of the motor power supply circuit of the apparatus.

Referring to the drawings: the bagging apparatus 10 is here shown as mounted on a caster base 11 so as to be readily movable with respect to a processing furnace in a plant producing perlite insulating granules to be bagged.

The illustrated apparatus 10 i largely of conventional construction, being essentially a standard type of valvebag filling machine. Since the construction of this ma chine is well known, no attempt is here made to illus trate or describe all its working parts in detail. The

usual cam mechanism (not shown) is disposed within the housing 12, Fig. 1, along with the drive motor 23, for producing vertical jarring or vibrating action of the bag-supporting foot 14 with respect to the guideway standard 15 in customary fashion during operation of the machine. pulley drive 17 of such cam mechanism for the purpose.

The apparatus it? fits below the discharge chute 125 of a collector for processed particles, or of some other source of the material to be bagged. In the bagging of perlite insulating granules, the discharge chute 13 usually leads into the hopper 19, Fig. 2, of the bagging apparatus, from a centrifugal ty-pe collector for the processed perlite, as discharged from a suitable heat processing furnace.

in the particular apparatus illustrated, a feed screw 20 i rotatably mounted within a substantially horizontal feed spout 21 for conveying material from the hopper 19 to a partially sealed, standard, valve-type bag, see 22, Figs. 3 and 4, fitted in customary fashion over the feed spout 2i and clamped in place by the usual mechanism 23. Feed of material to the bag is forced by feed screw 2%, as driven by belted connection with a second motor drive pulley 24. The bag is filled to maximum capacity prior to being closed and sealed in the customary manner by an attendant after he removes the filled bag from the spout 21.

Electrical controls for the drive motor 13 are contained in housing 25. Certain control components are not standard, and will be described in detail hereinafter in reference to the wiring diagram of Fig. 7.

For the purpose of restraining outward expansion of the broad panel walls of the bag 22 during the filling and jarring or vibrating operations, a pair of flat, rigid plates 26 are attached, in mutually spaced relationship,

to opposite branches 27a of a bifurcated structural frame 27, which extends from standard 15 in bracket formation. As illustrated, the branches 27a include upper and lower arms, respectively, which serve to receive mounting clips 28 projecting from the rear faces of the respective plates 26. Bolts 29, passing through receiving slots of the respective clips 28 and through receiving openings provided in the arms of the frame 27, serve to securely hold the respective plates 26 in suitably adjusted, mutually spaced positions on the frame, while bolts 39 secure the frame 27 rigidly to the standard 15 of the machine.

The forming plates 26 need comprehend only opposing major areas of the broad panel walls of the bag, intermediate opposite ends and opposite sides of the bag, see Figs. 3 and 4.

Since it is necessary that the bag-filling operation be halted at substantially the point at which the bag is filled to maximum capacity, and since I have found that this is best indicated by the exertion of greater than normal force by the material feed devicehere the feed screw 2t)I have provided the apparatus with an automatic stop control responsive to limited excessive current drawn by the drive motor 13. While this aspect of the apparatus is believed to be new, and is preferred, it should be realized that my method may be A motor drive pulley 16 is belted to the practiced by manually turning off the drive motor upon either direct observation of the working mechanism, or upon observation of a suitable indicator, such as a signal light, actuated in any well known manner by reason of limited excessive current drawn by the drive motor 13.

In accordance with my invention, I include an electrical relay in one leg of the power supply circuit of the motor 13. As illustrated in the diagrammatic showing of Fig. 7, where the motor 13 is three phase, the coil 31a of an electrical relay 31 is connected in one of the lines, L2, of the three electrical supply lines, L1, L2, and L3, leading to the motor. A standard overload protective device 32, provided with the customary timedelay heating coils 32a, is connected in the power supply circuit, as illustrated. A customary start and stop control button switch '33 is provided for manual operation, it being noted that only the start button is normally used, stopping of the operation being normally accomplishcd automatically by the relay 31.

The armature 31b of the control relay 31 is normally biased by a spring 34 to close the circuit by making with stationary contact 310, but is movable under the influence of coil 31a to break the supply of current to the motor 13 by interrupting the holding circuit of overload protective device 32. As here illustrated, such holding circuit includes the coil 32b of a standard magnetic contactor 320. The tension of spring 34 may be made greater or less by adjusting nut 35 on the threaded stem 36, thereby making it possible to set the device for response to any desired degree of excess current passing through relay coil 31a en route to the drive motor 13.

The demand, then, for excessive current by drive motor 13, so that it may exercise greater than normal feeding force on the screw 20 in the filling of a bag, automatically shuts oil the current supply and immediately halts the bag-filling operation. The relay may be set for very accurate and precise response to any tendency of the feed screw to overfill a bag by the exercise of undue compressive force on the contents of the bag. Yet, the bags will always be filled to the desired maximum capacity.

While size and capacity of the apparatus of the invention will, of course, vary in accordance with particular requirements, a typical installation in present use is equipped with a three phase, two horsepower drive motor whose rated normal current draw is approximately 3.3 amperes. During the normal filling period the current draw is approximately one ampere. The automatic shut-off relay 31 is ordinarily set to operate at current draw of between approximately 2.5 to 5 amperes, usually and preferably the lower value. The heating coils 32a of the standard overload protective device 32 ordinarily permit an overload of approximately 10%. Its rating is from approximately 2.99 to 3.5 amperes.

In the practice of my method by the use of the apparatus illustrated, the operator applies a bag 22 to the feed spout 21 of the apparatus in the customary manner, see Fig. 3. As so applied, the bag rests upon the foot 14, and, as it is being filled through operation of the feed screw 29, it and its contents are jarred or vibrated upwardly and downwardly in short strokes. This is the normal action of bag-filling apparatus of the type.

As the perlite granules are packed in the bag in this manner, they come under the influence of the forming or shaping plates 26. Outward expansion of the broad panel walls of the bag is thereby confined between parallel planes spaced apart to an extent determined in each in stance by the nature of the particular bag concerned. It should be noted that the adjustable mounting of the plates 26 is for this purpose.

Upon filling of the bag to a point where the packed perlite granules completely occupy substantially all of the available space within the bag, the tendency for exertion of greater than normal force by the feed screw 20 causes the drive motor 13 to draw more than the usual amount of current from the supply lines L1, L2, and L3, thereby energizing the relay coil 31a to pull armature 31b away from contact 310 against the adjusted tension of spring 34. Thus, the circuit supplying electricity to the drive motor is broken, and feed of material to the bag is abruptly halted, a is, also, jarring of the bag.

As illustrated in Fig. 6, the resulting bag of insulating granules is filled to maximum capacity, has the desired shape found most advantageous for handling, and po ssesses shape-retaining rigidity.

In connection with the apparatus of the invention, it should be noted that the function of the electrical relay 31 is to exercise control rather than protection. It is loaded by its spring 34 to an extent only slightly greater than balances the effect on relay coil 31a of normal operating current drawn from the supply lines by the drive motor 13. This loading is effectively less than the retarding factor incorporated in the overload protective device 32, i. e., the time-delay, heat-responsive elements 32a. Accordingly, while the device 32 stands constantly ready in usual fashion to protect the equipment against unusual overload, the control device 31 is acuated repeatedly, during normal operation of the apparatus, as called upon by the periodic draw of slightly greater than normal operating current.

The product of my method, it should be noted, is an article of commerce having distinct advantages over What was known heretofore. Because the filled and sealed bag is presh-aped and tightly packed, without slack, it possesses shape-retaining rigidity and immobility of individual granules relative to one another.

Both product and method are claimed in my copending divisional application for Patent Serial Number 624,876, filed November 28, 1956, and entitled Merchandise Pack of Fragile Insulating Granules and Method of Producing Same.

Whereas, this invention i here illustrated and described with respect to certain preferred embodiments thereof, it is to be understood that various changes may be made therein and that various other embodiments may be adopted, on the basis of the teaching hereof, by those skilled in the art, wtihout departing from the scope of the invention, as defined by the following claims.

I claim:

1. The combination, with bag filling apparatus for partially sealed, valve-type bags, including a rest for the bottom of the bag, means for vibrating said rest, a feed spout, forced feed means operable within said spout, an electrical drive motor, and a pair of mutually spaced, fiat, bag-forming plates operably disposed between said rest and said feed spout, of a drive control, comprising an electrical relay having an acutating coil connected in the electrical supply circuit of said drive motor, an armature connected a a switch in control relation to said supply circuit, and a load atttached to and normally biasing said armature into position electrically closing said supply circuit, said load having value efiectively less than normal for an overload protective device, but slightly greater than balances the effect on said coil of operating current normally supplied said drive motor.

2. The improvement of claim 1, wherein the armature is pivoted as a lever, the actuating coil being active on one arm of such lever, and wherein the load is a spring active on the other arm of the lever.

3. The improvement of claim 2, wherein adjustable means are provided for variably tensioning the spring.

4. In bag filling appartus equipped with an electrical drive motor, the improvement represented by an electrical overload-responsive control device comprising an electrical relay having an actuating coil connected in the electrical supply circuit of said drive motor, an armature connected in said supply circuit to open and close the same, and a load attached to and normally biasing said armature into circuit-closing position, said load having value only slightly greater than balances the efiect on said device of the electricity supplied to said drive motor during normal operation of the apparatus, but elfectively less than normal for an overload protective device.

5. The improvement of claim 4, wherein the armature is pivoted as a lever, the actuating coil being active on one arm of such lever, and wherein the load is a spring active on the other arm of the lever.

6. The improvement of claim 5, wherein adjustable means are provided for variably tensioning the spring.

7. In bag filling apparatus equipped with a three phase electrical drive motor connected in a three line electrical supply circuit, the improvement represented by an overload protective device connected across said electrical supply circuit, and an electrical overload-responsive control device for automatically stopping operation of said apparatus upon limited excessive current draw by said motor, said control device comprising an electrical relay, the coil of which is connected in one of said electrical supply lines and the armature of which is connected in make and break circuit relationship with said overload protective device, and a load attached to and normally biasing said armature into circuit-closing position, said load having value only slightly greater than balances the eifect on said device of the electricity supplied to said drive motor during normal operation of the apparatus, but efiectively less than normal for said overload protective device. 1

8. The combination recited in claim 7, wherein the overload protective device embodies a holding circuit, and wherein the armature of said electrical relay normally closes said holding circuit.

9. The improvement of claim 7, wherein the armature is pivoted as a lever, the actuating coil being active on one arm of such lever, and wherein the load is a spring active on the other arm of the lever.

10. The improvement of claim 9, wherein adjustable means are provided for variably tensioning the spring.

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